The present invention relates to remotely operable latching assemblies. More particularly, the present invention relates to remotely operable latching assemblies that utilize magnetic forces to supply both the latching force and the releasing force for the latch assembly.
In many applications it is desirable to utilize a latching system to releasably secure two or more structures together. In particular, spaced-based applications often utilize remotely operable latch systems to releasably hold one component to another. For example, a payload may be releasably attached to a space launch vehicle for launch and released once orbit is attained. Alternatively, the payload itself may utilize remotely operable latches for one or more purposes, such as deploying solar panels after separation from a launch vehicle.
Various remotely operable latching systems are available for space-based applications. For example, a number of pyrotechnic separation systems exist that utilize some sort of explosive charge to release objects held relative to one another. One drawback of these systems is the inability to test the actual components that will be utilized for the space-based application. As will be appreciated, once these pyrotechnic systems are xe2x80x9cactivated,xe2x80x9d one or more of their components is destroyed. Therefore, until the moment of activation, it is unknown whether these untested components will properly function.
It is an objective of the present invention to provide a remotely operable latch assembly for releasably holding two objects relative to one another.
It is a further objective of the present invention to provide a latch that provides a mechanically advantageous holding force for securing two objects together.
It is a further objective of the present invention to provide a remotely operable latch assembly having little or no power requirements while in a latched position.
It is a further objective of the present invention to provide a remotely operable latch assembly that is resettable to allow for non-destructive testing of the latch assembly.
It is a further objective to provide a latch assembly that is simple to manufacture and that utilizes readily obtainable parts.
These and additional objectives are achieved by the present invention which provides an electromagnetic latching assembly operable to apply a mechanically advantageous force for holding a first structure relative to a second structure and which may be remotely actuated to release these structures from one another. In this regard, a first retaining force is utilized to maintain the latching assembly in a closed position while the latching assembly secures the first and second structures together with a second holding force. Preferably, the retaining force will be smaller than the resulting holding force by at least an order of magnitude. The latching assembly utilizes a magnet to apply the retaining force that maintains the latch in the closed position, and a selectively actuateable electromagnet to open the latch assembly and thereby release the first and second structures from one another. Generally, the present invention is embodied in a latching assembly that utilizes at least one, and more preferably two levers interconnected to a frame to provide the mechanically advantageous holding force.
An electromagnetic latch assembly of a first aspect of the present invention includes: a frame that is interconnectable with a first member and contains at least a first aperture; a first lever interconnected to the frame that is pivotable between a first holding position and a first release position; a second lever interconnected to the frame that is pivotable between a second holding position and a second release position and comprising at least a second aperture; a permanent magnet associated with the first lever; and an electromagnet operatively associated with the first lever. Each of the first and second levers contains a free end that is operable to pivot relative to the frame. Further, when the latch assembly is in a closed position, the free end of the second lever is retained under the free end of the first lever. When the latch assembly is in the closed position, the permanent magnet applies a holding force that maintains the first lever in the first holding position and thereby holds the second lever in the second holding position. When the first and second levers are in the first and second holding positions, the aperture contained within the frame as well as an aperture associated with the second lever are disposed in an adjoining relationship and collectively define a third aperture. In this closed position, a second structural member may be disposed through this third aperture and restrained from being pulled back through this third aperture. In this regard, the first and second structural members are interconnected when the latch assembly is closed (i.e., the first and second levers are in the first and second holding positions).
Various refinements exist of the features noted in relation to the first aspect of the present invention. Further features may also be incorporated in the first aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. As noted, both the first and second lever are pivotable between holding and release positions. Any way of interconnecting the first and second levers to the frame in a manner that allows them to pivot between these positions may be utilized. Irrespective of the type of interconnection, the first and second levers will pivot about first and second axes, respectively. In one embodiment, the free end of the first lever will extend at least partially toward the pivot axis of the second lever and the free end of the second lever extends at least partially toward the pivot axis of the first lever. This allows a portion (e.g., the free end) of the second lever to be retained beneath at least a portion of the first lever. In a further embodiment, the axes of these levers will be substantially parallel to one another allowing the first and second lever to pivot directly towards one another. In this embodiment, the free end of the second lever will be restrained beneath a portion of the first lever.
In order for the free end of the second lever to be retained beneath the first lever when the axes of the levers are substantially parallel, the length of the second lever, as measured between the pivot axis of the second lever and the free end of the second lever, will be shorter than the distance between the pivot axes of the two levers. In a further embodiment of the parallel axes orientation, the first lever will be long enough to extend beyond the pivot axis of the second lever. In this configuration, the extending free end of the first lever may be restrained to maintain the latch assembly in the closed position. In this regard, the lever arm between where a restraining force is applied to the first lever and the pivot axis of the first lever will be greater than the lever arm between where the free end of the second lever is restrained beneath the first lever and the pivot axis of the first lever. That is, a mechanically advantageous use of leverage may be realized.
The permanent magnet and electromagnet of the assembly are utilized to restrain the first lever in the first holding position when the latch assembly is closed and provide a releasing force that allows the first and second levers to move from their holding positions to their release positions, respectively. In this regard, the permanent magnet may be attached in any appropriate manner to any point along the length of the first lever such that the magnet is able to magnetically couple to a ferromagnetic surface and restrain the first lever in the holding position when desired. In order to maximize the restraining force provided by the permanent magnet to the first lever, the permanent magnet will generally be attached near or toward the free end of the first lever. That is, the distance between the magnet and the pivot axis of the first lever will be maximized to increase the leverage available to the magnetic restraining force.
In one embodiment, the permanent magnet of the assembly couples directly to the ferromagnetic core of the electromagnet when the first lever is in the first holding position (i.e. when the latch is closed). In this configuration, the electromagnet may be in an unactivated state when the permanent magnet is restraining the first lever in the holding position such that the latch assembly utilizes no electrical power when closed. In this embodiment, activation of the electromagnet will release the magnetic coupling of the permanent magnet to the ferromagnetic core and allow the first lever to pivot from the first holding position to the first release position, thereby allowing the second lever to pivot from the second holding position to the second release position. This will cause the second structural member to be released from the first structural member. As will be appreciated, activating the electromagnet may cause the ferromagnetic core to have a magnetic flux that will repulse the previously coupled permanent magnet. That is, the activated electromagnet and permanent magnet will have like magnetic fluxes and repel one another.
As noted, the subject first aspect utilizes a frame that contains a first aperture that, in combination with an aperture on the second lever, defines a third aperture that is utilized to hold the second structural member relative to the first structural member. In one embodiment, the aperture of the frame is contained within a pivotable support platform. This pivotable support platform is disposed in an adjoining relationship with the second aperture of the second lever when the latch assembly is closed. For example, the support platform as well as the second lever may each contain a half circular indention (i.e., aperture) which, when disposed in the adjoining relationship, defines a single circular aperture. Other shapes for the aperture in each of the support platform and the second lever may be appropriate. As will be appreciated, while the latch is closed, the third aperture may be sized to prevent, for example, the flange of a bolt associated with the second structural member from being pulled therethrough. In order to release the second structural member, the collectively defined third aperture may be separated or the size thereof somehow expanded to allow the second member to pass therethrough.
In order to separate or expand the collectively defined third aperture, one or both of the second lever aperture and frame aperture may be moved away from the other structure to eliminate the adjoining relationship between the frame aperture and the second lever aperture. For example, when the second lever moves from the holding position to the release position (i.e., when the latch assembly is opened), the second lever aperture may rotate away from the frame aperture to separate or increase the size of the collectively defined third aperture. Additionally, when the pivotable support platform is utilized, both the second lever and the support platform may move away from one another to eliminate the adjoining relationship. In this regard, any assembly that allows the two structures to move away from one another may be utilized. In one embodiment, a first gear is mounted relative to the support platform and a second gear is mounted on the second lever. Any appropriate means of transferring rotation between the gears may be utilized to translate the rotation from the gear of the second lever to the gear of the support platform. For, example, chains or intermediate gear structures may be utilized. In one embodiment, the teeth on the two gears are directly meshed. In this embodiment when second lever moves from the holding position to the release position, its gear will rotate and the gear on the counter support platform will rotate in an opposite direction. This rotation in the opposite direction will allow the support platform to pivot in an opposite direction from the support lever. Accordingly, the collectively defined aperture may be separated or expanded to allow the second support structure to pass therethrough.
According to a second aspect of the present invention, a remotely operable latch assembly is provided. This remotely operable latch assembly comprises: a frame; a support lever pivotably mounted to the frame for releasably supporting a load when the support lever is in a support position; a restraint lever pivotably mounted to the frame for applying a holding force to maintain the support lever in the support position when the restraint lever is in a closed position; a permanent magnet that is operatively associated with the restraint lever to provide a magnetic restraining force to hold the restraint lever in the closed position; and a remotely actuateable electromagnet for selectively providing a magnetic flux to counteract the magnetic restraining force applied by the permanent magnet to the restraint lever and thereby allow the restraint lever to move from a closed position to an open position. As will be appreciated, when the restraint lever moves to an open position, the support lever is able to release its supported load by moving from a support position to a release position.
Various refinements exist of the features noted in relation to the second aspect of the present invention. Further features may also be incorporated in the second aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. In one embodiment of the second aspect of the present invention, the latch assembly is operable to provide a mechanically advantageous holding force to hold a load as may be applied by a first structure relative to the frame which may be interconnected to a second structure. That is, the latch assembly may be utilized to releaseably hold two structures together. In this regard, the support lever and the restraint lever advantageously utilize leverage about their respective pivotal mountings to provide an increased holding force between the two structures. For example, the support lever is operable to support the loading force (e.g., as applied by a bolt interconnected to a first structure) at a first point along its length, while the holding force utilized to hold the support lever in the support position is applied to a second point along the length of the support lever. Particularly, the loading force is applied at a first point that is nearer to where the support lever is pivotally mounted than is the second point where the holding force is applied. In this regard, the holding force utilizes a longer lever arm to counteract the loading force. It will be appreciated that the holding and loading forces may be applied on one side of the lever in relation to its pivotal mounting or the pivotal mounting may be between where the holding and loading forces are applied to the lever. What is important is that the holding force is able to utilize a longer lever arm in relation to the pivotal mounting to provide a mechanical advantage.
Similarly, the restraint lever provides advantageous leverage for the magnetic restraining force (applied by the permanent magnet when the latch assembly is closed) to provide a greater holding force as applied to the support lever. That is, the magnetic restraining force is applied to the restraint lever at a distance further from its pivotal mounting than the holding force is applied to the support lever. Again, both forces may be applied to the restraint lever on the same side of the lever in relation to its pivotal mounting, or the pivotal mounting may be between where the forces are applied to the lever, so long as the restraint force utilizes a longer lever arm.
As noted, the permanent magnet of the second aspect is associated with the restraint lever and provides a magnetic restraining force to hold the restraint lever in the closed position. In one embodiment, the permanent magnet is magnetically coupled directly to the electromagnet when the restraint lever is in the closed position. In this regard, at least one of the magnets will be fixedly attached to the restraint lever. Due to the necessary electrical wiring of the electromagnet, the permanent magnet will generally be fixedly attached to the restraint lever. Irrespective of which magnet is affixed to the restraint lever, when the latch assembly is closed, the electromagnet will not be actuated and produces substantially no magnetic flux. In this regard, the permanent magnet is able to magnetically couple to the ferromagnetic core of the electromagnet. However, upon selective activation of the electromagnet, which may be done remotely, the electromagnet will produce a like magnetic flux at the interface with the permanent magnet. That is, the electromagnet will provide a repulsive magnetic flux directly to the permanent magnet and thereby release the magnetic restraining force that holds the restraint lever in the closed position. Furthermore, this repulsive magnetic flux may be utilized to initiate the movement of the restraint lever from the closed position to the open position.
As noted, the electromagnet is remotely actuateable. This remote operation allows the latch assembly to be utilized in hazardous environments, space-based applications, and any other environment where direct access to the latching assembly is not feasible. Any way of remotely actuating the electromagnet, which generally comprises completing an electrical circuit through the electrical windings, may be utilized.
According to a third aspect of the present invention, a mechanically advantageous electromagnet latch assembly for holding a first structure member relative to a second structure member is provided. The mechanically advantageous latch assembly includes a frame for mounting to the first structural member; a lever that is pivotally mounted to the frame for applying a holding force to a second structural member when the lever is in a closed position; a permanent magnet operatively associated with the lever for providing a magnetic restraining force to hold the lever in a closed position; and an electromagnet operatively associated with the lever for selectively providing a magnetic flux to release the magnetic restraining force. In the subject third aspect, the electromagnet and the permanent magnet are disposed relative to one another such that they are magnetically coupled when the lever is in the closed position.
Various refinements exist of the features noted in relation to the third aspect of the present invention. Further features may also be incorporated in the third aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. In order to apply a restraining force to hold the lever in the closed position, at least one of the magnets is mounted to the lever while the other magnet is mounted to the frame of the latch assembly. By mounting the magnets so that they are magnetically coupled when the lever is in a closed position, a mechanically advantageous latch assembly can be provided which utilizes no electrical energy while in the closed position. That is, the electromagnet may be selectively actuated to counteract the magnetic restraining force applied by the permanent magnet by providing a repulsive magnetic field when magnet separation is desired to open the latch assembly. As will be appreciated, this provides a passive latch assembly which utilizes no electrical energy while the latch assembly holds the first and second structures together. Furthermore, the disposition of the permanent magnet and electromagnet so that they magnetically couple allows complete elimination of the magnetic restraining force applied to the lever by selectively actuating the electromagnet.
In order to provide a mechanically advantageous force for holding the first structure member to a second structure member, the latch assembly utilizes leverage provided by the lever. That is, the lever applies a holding force to the structure nearer to where it is pivotally mounted than to where the magnetic retraining force is applied to the lever. In this regard, the magnetic restraining force utilizes a longer lever arm and is able to counteract a larger holding force.
According to a fourth aspect of the present invention, a method for operating a latch assembly containing first and second pivotable levers is provided. The method comprises the steps of first restraining the first lever in a first holding position, which may be a closed position for the latch assembly, utilizing a magnetic coupling. This first restraining step is utilized to secondly restrain the second lever in a second holding position. This restraining of the first and second levers releaseably interconnects the first and second members to one another. At a predetermined time, this interconnection may be terminated by terminating the magnetic coupling. Termination of the magnetic coupling allows the first lever to pivot to a first release position and the second lever to pivot to a second release position. Combined, the pivoting of the first and second levers to first and second release positions releases the first member from the second member.
Various refinements exist of the features noted in relation to the fourth aspect of the present invention. Further features may also be incorporated in the fourth aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. For instance, using the magnetic coupling in the first restraining step may comprise coupling one pole of a permanent magnet to the ferromagnetic core of a non-activated electromagnet. That is, one of the magnets may be affixed to the first lever and magnetically coupled to the other magnet using the magnetic force of the permanent magnet. In this regard, the terminating step may be achieved by activating the electromagnet so that the same polarity exists on both magnets where the magnets are coupled. As will be appreciated, these like magnetic poles will repulse one another. This repulsive force may also be utilized as a contributing force to pivot the first lever from the first support position to the first release position and therefore aid in separating the first and second members.
Each of the levers is operable to pivot between holding and release positions. In this regard, the levers contain a pivot point along their length and at least one free end that is operable to pivot about this pivot point. Accordingly, lo the steps of restraining these levers may comprise restraining one of their free ends to prevent their pivoting. For example, the permanent magnet may be attached to a free end of the first lever and be operable to restrain that end of the lever in a fixed position. In one embodiment, restraining the second lever step comprises restraining a free end of the second lever beneath a portion of the first lever when the first lever is restrained. Preferably, both restraining steps will comprise applying a restraining force to each respective lever at a point more distally located on that lever than the application of any forces/loads utilized to interconnect the first and second members relative to one another.
Interconnection of the first and second members, may be done in any appropriate manner that allows the latch assembly to releaseably hold the members together while the first and second levers are in the first and second holding positions, respectively. In one embodiment, the interconnection step comprises passing a portion of one of the members, such as a bolt affixed with one of the members, through an aperture at least partially defined by the second lever. In this interconnection step, part of the member (e.g., bolt) will be restrained from passing through the aperture while the second lever is in the second holding position. Further, this portion of the member passing through the aperture may be loaded (e.g., tightening a bolt) to securely interconnect the members together. This loading may apply a force to the second lever that may be utilized to pivot the second lever to the second release position upon termination of the magnetic coupling. Regardless, when the second lever pivots to the release position, the disconnecting step will include the previously restrained part of the member disposed through the aperture passing relative to the aperture so the first and second members are disconnected.